The defensive problems surfaced once again for the Portland Timbers Sunday afternoon.

The Timbers gave up a disappointing four goals en route to a 4-2 loss to rivals Seattle Sounders in front of a crowd of 20,814 at Providence Park.

"We didn't manage situations defensively very well tonight," Timbers coach Caleb Porter said. "There were a lot of chances that they got that shouldn't have been chances. It was poor defending."

Critical defensive mistakes have been an issue for the Timbers all season. The Timbers are third in MLS in goals conceded with 43.

The poor defending prompted Portland to sign former English Premier League defender Liam Ridgewell as a designated player at the end of June and Ridgewell has certainly provided veteran leadership and consistency on the back line since his debut on July 18.

Heading into Sunday's match, the Timbers had gone 3-1-1 in games where Ridgewell had started on the back line.

But on Sunday, Portland failed to adequately defend the counter attack or prevent Seattle stars Obafemi Martins and Clint Dempsey from putting the ball in the back of the net.

"I think a couple of the goals were counter attack goals," Ridgewell said. "Sloppy from ourselves because it's something where we knew they were going to try to pounce on us because we were trying to get at them."

Martins got on the end of a cross from midfielder Brad Evans on a counter attack in the 18th minute and tapped the ball into the back of the net to give Seattle the 1-0 lead.

"First chance, we're up the field and they're behind us," Porter said, "and it's a cross and it's a goal."

Martins then created Seattle's second goal when he found the ball after a Timbers corner and made a run toward goal in the 34th minute before finding Dempsey at the top of the box.

Dempsey dribbled around Timbers goalkeeper Donovan Ricketts and past Timbers defender Michael Harrington before tapping the ball into the net to give the Sounders a 2-0 lead.

"I think the ball got popped out to Martins, and then it's about trying to delay him as much as possible and, hopefully, our guys get back," Timbers defender Danny O'Rourke said. "When I was delaying Martins I didn't even see Dempsey coming that way. It was a probably a good run by him and a good finish, but that's one of the things we need to straighten out."

For the rest of the match, the Timbers continued to have trouble stopping Seattle's world-class strikers.

Dempsey added an assist in the second half on Seattle's third goal, while Martins used some nifty footwork to get behind Portland's defense and score Seattle's fourth and final goal.

For three straight games, Porter has started a back line of Ridgewell and Norberto Paparatto at center back and O'Rourke and Harrington at outside back.

Porter said he has had O'Rourke and Harrington stay back to give the Timbers the best opportunity to put together strong defensive performances.

"We've been going with a little bit more stay at home outside backs because we haven't been good enough defensively," Porter said. "The thought is, 'Can we be organized and have a little bit more of a back four that's intact?' It didn't work out today."

The Timbers won't have a lot of time to work through their defensive mistakes. They desperately need the defense to rebound and put together a good performance against Western Conference rivals Vancouver Whitecaps next Saturday.

"You come up against two class strikers and they are a very good team," Ridgewell said. "We got to try to manage that better. The only way we're going to get better is working on it during the week and making sure we cut out (the mistakes) for next week."